17,343 research outputs found
Entanglement versus mixedness for coupled qubits under a phase damping channel
Quantification of entanglement against mixing is given for a system of
coupled qubits under a phase damping channel. A family of pure initial joint
states is defined, ranging from pure separable states to maximally entangled
state. An ordering of entanglement measures is given for well defined initial
state amount of entanglement.Comment: 9 pages, 2 figures. Replaced with final published versio
Automatic speaker segmentation using multiple features and distance measures: a comparison of three approaches
This paper addresses the problem of unsupervised speaker change detection. Three systems based on the Bayesian Information Criterion (BIC) are tested. The first system investigates the AudioSpectrumCentroid and the AudioWaveformEnvelope features, implements a dynamic thresholding followed by a fusion scheme, and finally applies BIC. The second method is a real-time one that uses a metric-based approach employing the line spectral pairs and the BIC to validate a potential speaker change point. The third method consists of three modules. In the first module, a measure based on second-order statistics is used; in the second module, the Euclidean distance and T2 Hotelling statistic are applied; and in the third module, the BIC is utilized. The experiments are carried out on a dataset created by concatenating speakers from the TIMIT database, that is referred to as the TIMIT data set. A comparison between the performance of the three systems is made based on t-statistics
In-Situ absolute phase detection of a microwave field via incoherent fluorescence
Measuring the amplitude and the absolute phase of a monochromatic microwave
field at a specific point of space and time has many potential applications,
including precise qubit rotations and wavelength quantum teleportation. Here we
show how such a measurement can indeed be made using resonant atomic probes,
via detection of incoherent fluorescence induced by a laser beam. This
measurement is possible due to self-interference effects between the positive
and negative frequency components of the field. In effect, the small cluster of
atoms here act as a highly localized pick-up coil, and the fluorescence channel
acts as a transmission line.Comment: 13 pages, 5 figure
Extreme vortex pinning in the non-centrosymmetric superconductor CePtSi
We report on the vortex dynamics of a single crystal of the
non-centrosymmetric heavy-fermion superconductor CePtSi. Decays of the
remnant magnetization display a clean logarithmic time dependence with rates
that follow the temperature dependence expected from the Kim-Anderson theory.
The creep rates are lower than observed in any other centrosymmetric
superconductor and are not caused by high critical currents. On the contrary,
the critical current in CePtSi is considerably lower than in other
superconductors with strong vortex pinning indicating that an alternative
impediment on the flux line motion might be at work in this superconductor.Comment: 4 pages, 5 figure
Assessing the role of optical head-mounted displays in education: an investigation of Google Glass in creating learning portfolios and providing feedback
Technology Enhanced Learning is a field that has seen impressive developments over the past few years. Educators have experimented with the use of web technologies, introduced innovative e-learning approaches, extended the role of virtual learning environments and introduced learning analytics. The authors’ research aims to investigate how ubiquitous computing and augmented reality can further support students in a range of learning activities. In particular, this paper discusses a research study in the role of Optical Head-Mounted Displays (OHMD) in education. Emphasis is given on how the technology can enhance learning through the provision of additional support via augmented reality.
The paper describes how OHMD, and more specifically Google Glass has been used by students in a Higher Education Institution as part of their assessment. The research aim is twofold as it considers (i) the role of OHMD in supporting students during the creation of learning portfolios which can be used for formative and summative assessment, and (ii) the impact OHMD technology has in providing alternative ways of feedback. The scope of the research is to assess the suitability of the technology, the benefits that can be introduced in educational contexts as well as the perceived value of the technology from the learners’ point of view.
The first part of the study described in the paper describes how learners have used OHMD to construct a portfolio of learning evidence through cooperative evaluation of their work. In particular the study involved students using Google Glass to take snaps of their work, while recording a video diary of their contribution towards group coursework. Users reflected on the experience in terms of ease of use, simplicity and usefulness. They also evaluated the effectiveness of using OHMD during specific tasks including reading, writing and browsing.
The second part of the study is focused on providing feedback by using OHMD to attach vignettes on pictures of presentations. The technology is used for commenting on presentation content and delivery, while it is investigated as an alternative for providing feedback on practical activities. The paper also provides a detailed discussion of preliminary findings from the pilot with 92 participants studying at first and final years of a University degree
Using Optical Head-Mounted Devices (OHMD) for provision of feedback in education
This paper discusses the investigation of using Optical Head-Mounted Devices (OHMD) for provision of feedback in education. In particular it discusses an investigation in the use of Google Glass in real time training and mentoring. First the papers discusses an application created for the device for provision of feedback on student presentation. Next the paper presents, the research conducted with an experiment involving ninety-two participants testing the application in a real life scenario
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